Gatherers (skinners/herbalists/miners without leatherworking/alchemy/blacksmithing): Save your gathered items until you get a stack, then sell them at the Auction House.

Levelling up by doing nothing but grinding is one way to ensure that you have the money to buy your mount when you reach the required level (by selling/auctioning the drops). However, grinding is repetitive, and this method typically requires a good knowledge of grinding spots. You may also have to compete with other players grinding in the same hot-spot. One example of a good spot is an area where there are a lot of humanoids that drop money and various raw cloth, which is always in high demand. Grinding also improves your likelihood of looting rarer drops that are worth large amounts of gold in the auction house.

Even if you choose to level and raise money simply by grinding, be sure to complete enough quests with your home faction to raise your reputation - with the Patch 2.3.0 (13-Nov-2007): All vendors with an associate faction now give discounts at all levels above neutral.